2-amino-4, 6-dinitrobenzothiazole



2 Claims.

This invention relates to the compound 2-amino-4,6-dinitrobenzothiazole, and valuable azo dyes made therefrom.

2-amino-4,6-dinitrobenzothiazole has the following structure:

7 \C-NH2 It has been now found that this compound can be prepared bynitration of 2-aminobenzothiazole or 2-amino-4-nitrobenzothiazole, whichlatter compound has the structure:

It has further been found that the 2-amino-4,6-dinitrobenzothiazole ofthis invention may be diazotized and coupled with any of a variety ofcoupling agents to produce valuable azo dyes which are especiallyeffective in dyeing cellulose acetate, nylon and Dacron fibers.

Diazotized 2-amino 4,6-dinitrobenzothiazo1e can be coupled with phenols,such as phenol, cresols, naphthols, resorcinol, guaiacol, etc., to givegenerally yellow-torange dyes. It can also be coupled with activemethylene compounds such as acetoacetanilide, 1-phenyl-3-methyl-pyrazolone, and substitution (especially halogenation) productsthereof, to give also generally yellow to orange dyes.

Of special interest, however, are the azo dyestuffs preparable bycoupling diazotized 2-amino-4,6-dinitrobenzothiazole with tertiaryaromatic amines such as dimethyl aniline, diethylaniline, phenyldiethanolamine, m-tolyl diethanolarnine, phenyl ethyl ethanolamine,N-phenyl-N- beta-cyanoethyl ethanolamine, N-(Z-methoxy-S-methyl) phenyldiethanolamine, N-phenyl-N-butyl ethanol-amine, N-ethyl N (2,3dihydroxypropyl) m-toluidiue, N- (2- methoxy 5 acetylaminophenyl)-diethanolamine, ethylbeta-cyanoethyl-aniline, and N-phenyl morpholine,which dyes give fast violet, blue, and green shades on celluloseacetate, Dacron and nylon.

2-amin0-4,6-dinitrobenzothiazole can be prepared by nitration ofZ-aminobenzothiazole or 2-amino-4-nitrobenzothiazole. The followingExamples 1 and 2 illustrate the preparation of this new and valuableintermediate.

EXAMPLE 1 Nitration of 2-Amin0-4Nitr0benz0thiaz0le Thirty-nine grams ofZ-aminoA-nitrobenzothiazole is dissolved in 400 ml. of 96% sulfuricacid, the solution is cooled to 3-5 C. and then, over a period of twentyminutes, a mixture of 18 grams of 70% nitric acid with 200 ml. of 96%sulfuric acid is added with stirring. After addition of the nitrationmixture is complete, the'reaction is stirred for one hour at 0 C. andthen the temperature is allowed to rise, over a period of two hours, to19 C.

3 mm Fatentecl May 21, 1963 Stirring is continued throughout this twohour interval and for an additional one and one-half hours, during whichthe temperature is raised to 99 C. during the first hour and thenmaintained at 99 C. for one-half hour. After cooling overnight thereaction mixture is added slowly to enough of an ice-water mixture tomake a final volume of 8000 ml. The lemon yellow precipitate iscollected by filtration and washed with water until neutral to litmus.It is then suspended in dilute aqueous sodium bicarbonate solution (16.8grams of sodium bicarbonate in 1500 ml. water) and then filtered andwashed neutral to litmus. It is then dried at 50 C. to give 45 grams(93.8% of theory) of product which melts at 334-337 C. withdecomposition. An elemental-analysis shows 23.22% nitrogen, 35.26%carbon, 1.83% hydrogen and 13.77% sulfur (calculated for dinitro Z-aminobenzothiazole: 23.35% nitrogen, 35.00% carbon, 1. 67% hydrogen and13.33% sulfur).

2-amino-4-nitro-benzothiazole used in the above preparation is obtainedby the following series of reactions in accordance with prior artteachings:

{ H01 I 08012 21101 (56% y eld) NHz N=C=S NH: v (56% yield) N==O=SNH-CNH1 NO: l lo:

S Bra in CHCla ll 5 NH-C-NH:

S\ m /ONH2.HBI HBr N Y S\ S l /ONH2.HBr NaOH G O-NH:

N I N N02 N02 The yield of 2-amino-4-nitro-benzothiazole is 70%, basedon the amount of o-m'trophenylthiourea used in reaction number 3.

EXAMPLE 2 Nitration of Z-Aminobenzothiazole Into a five-liter,three-neck flask fitted with :a mechanical stirrer, a thermometer, and adropping funnel is placed 1500 ml. of concentrated (-96%) sulfuric acidwhich is then cooled with stirring to below 10 C. While keeping thetemperature below 10 C., 150 g. of 2-aminobenzothiazole is addedgradually. After the Z-aminobenzothiazole has all dissolved, 1240 g. ofmixed acid (made from 140 g. of nitric acid and 1100 g. of 20% oleum)are added While keeping the temperature below 5 C. Stirring is continuedfor one hour at -5 C., and then at room temperature .overnight. Themixture is then heated to 100 C. and stirred for three hours at thistemperature, after which it is cooled to 25 C., and poured into ice andwater contained in a 30-liter battery jar. The product precipitates as abright yellow powder which is filtered, washed free of acid, and driedover night at 50 C. The product melts with decomposition at 320325 C.,.with some preliminary shrinking at 300 C. Elementary analysis shows22.84% N; calculated for C H O N S, 23.35. Ten grams of the above crude2-amino-4,6-dinitrobenzothiazole are purified by four recrystallizationsfrom 600 ml. of nitrobenzene. -In this way, 5.64 grams of yellow solidis obtained which contains 23.13% N, melts at 33-1 334 C., and shows nomelting point depression when mixed with the product of Example 1. Asabove pointed out, the 2-amino-4,6-dinitrobenzothiazole of thisinvention can be employed as a chemical intermediate and is especiallyuseful .in the preparation of azo dyestufis. Examples 3-14 illustratethe preparation of such novel dyes.

EXAMPLE 3 V S i i H OIN on,ono

omomon N CHa h v No,

Diaz0tizati0n.-A solution of 4.80 g. of 2-amino-4,6-dinitrobenzothiazole in 50 ml. of 85% phosphoric acid is placed in a 250ml. three-neck flask and cooled with stirring in an ice-salt bath tobetween 15 and 12 C. While keeping the temperature Within these limits,1.52 g. of sodium nitrite dissolved in 5 ml. of water is added over aperiod of'20 minutes, after which the mixture is stirred for anadditional 75 minutes at about --13 C.

Coupling.m-Tolyl diethanolamine (3.90 g.) is dissolved in 150 m1. ofwater and 2 ml. of 37% hydrochloric acid contained in an 800 ml. beaker.The above diazotized 2-amino-4,6-dinitrobenzothiazole solution is nowadded over a ten-minute period with vigorous stirring. The temperatureof the reaction mixture is kept between 4 C. and 0 C. by addition ofice. A deep blue precipitate forms, and the mixture is stirred foranother 30 minutes, keeping the temperature below 5 C. A solution of60.5 g. of sodium acetate in 200 ml. of water is then added slowly,keeping the temperature below 13 C. At this stage, the mixture testsgray, i.e., is neutral, to Congo red. It is stirred for three hourslonger, and filtered. The intensely blue solid is collected, washed wellwith water until the washings are neutral to litmus, and dried at 50 C.A yield of 4.60 g., representing 51.9% of theoretical, is obtained. Thedye may be purified by recrystallization from aqueous acetone.

Dispersion.0ne gram of the above dye is ground with 0.50 gram of sodiumlignin sulfonate (Marasperse N),

0.50 gram of Cyclopon AF, and a little water. The mixture is then driedat 50 C. and pulverized.

Dyeing-Theproduet dyes acetate, nylon, and Dacron in blue shades. Thedyeings of acetate give strong blue shades with good build-up. Thefastness to light, gas, sublimination, hot press, and wash (AATCC WashTest #3) are good. The dyeings are dischargeable.

7 EXAMPLE 4 omomon Diazotization is conducted in the same manner asdescribed in Example 3.

Coupling-3.30 g. of N-ethyl-N-beta hydroxyethylaniline, 2.0 ml. of 37%hydrochloric acid, and 150 ml. of water are stirred together in a1-liter beaker until dissolution'is complete. The diazonium solution isthen'added with vigorous stirring over a period of 10 minutes, thetemperature being maintained at 0 C. by addition of ice as necessary. Ablue precipitate is formed. The suspension'is stirred for 45 minutes at05 C. Then a solution of 60.5 g. of sodium acetate in 200 ml. of wateris added over a period of 10 minutes, the temperature being v maintainedbetween 5 and 14 C. The liquid is neutral (i.e., tests gray) to Congored. After three additional hours of stirring at 1418 C., the solid isfiltered 0E, washed with water until the washings are neutral to litmus,and dried at 50 C. A yield of 5.00 g., representing 60.1% oftheoretical, is obtained.-

Dz'spersi0n.'Ihis dye is as in Example 3.

Dyeing.This dye produces strong blue shades on acetate, nylon, andDacron, with good build-up. The

dispersed in the same manner dyeings are dischargeable.

. period ofseven minutes, adding ice as necessary to keep' EXAMPLE 5OHzOHzO (MN i N% a r omomon ethylaniline are dissolved in 150 ml. ofwater and 4.0 ml.

of 37% hydrochloric acid contained in a one-liter beaker. 'I'hesoluti onis cooled to'belo'w 0 C. by addition of ice, and the diazonium solution.is added gradually over a the. temperature below 0 C. A'blue-violetprecipitate forms, and the .slurry is stirred for one hour with thetemperature between 0 and 11 C. A solution of 68.6 g. of sodium acetatein 200 ml. of water is nowadded slow ly, which makes the solutiontestgrayto Congo red. The slurry is stirred for an additional two hours andthen filtered. The solid is washed with water until the washings areneutral to litmus, and then dried in an oven at 50 C.- 5.50 g. of ablue-violet product is obtained, indicating a yield of 62.4% oftheoretical. Dispersion is efiected as in Example 3. Dyeings on nylonare reddish-blue; on Dacron, a violet color. Acetate is dyed a violetcolor with good build-up and goodilightfastness.

. EXAMPLE 6 CHzCHaOH OzN . Diaz0;iZati0n.-A solution of 4.80 grams of2-amino 4,6 -din-itrobenzothiazole in 50 ml. of phosphoric acidcontained in a 250 ml. S-neck flask is cooled with stirring in anice-salt bath to 14 C. 1.40 grams of sodium nitrite is added as a solid,and stirring is continued a for three hours, keeping the temperaturebetween -l7 and -.10 C. v r

C0upling.m-TOlyl diethanolamine (3.90 g.) is dissolved in a mixture of 2ml. of 37% hydrochloric acid and ml. of water contained in a 1000 ml.beaker. The solution is cooled with ice to below 0 C., and thediazotized amino-dinitrobenzothiazole is added over a 53 solidseparates. After stirring the mixture for 45 minutes at about C., themineral acid is neutralized by addition of 60.5 g. of sodium acetatedissolved in 200 ml. of water. The neutralized mixture (testing gray toCongo red) is stirred for 2 /2 hours and filtered. The solid is washedneutral to litmus and dried at 50 C. A yield of 5.08 g., correspondingto 56.9% of theoretical is obtained. The product is identical inproperties and behavior with that of Example 3.

EXAMPLE 7 Diazotization is effected as described in Example 6.

Coupling.N-phenyl-diethanolamine (3.62 g.) is dissolved in 150 ml. ofwater and 2.0 ml. of 37% hydrochloric acid contained in a one-literbeaker. The solution is cooled to below 0 C., and the diazonium solutionis added over a period of minutes, stirring vigorously and keeping thetemperature below 0 C. by addition of ice as necessary. A blueprecipitate forms, and the resulting suspension is stirred for 2 /2hours. There is then added slowly a solution of 60.5 g. of sodiumacetate in 200 ml. of water. The suspension now tests gray to Congo red.It is stirred for 23 hours at room temperature, heated briefly to 85 C.,and allowed to cool to room temperature. The intensely blue solid isisolated by filtering, washing neutral to litmus, and drying at 50 C.The yield is 5.40 g., equivalent to 62% of theoretical.

Dispersion is etfected as in Example 3.

Dyeing-The product of this example dyed acetate, nylon and Dacron inblue shades. The dyeing on acetate is strong deep blue with goodbuild-up and has good fastness to light, gas and sublimation. The dyemgsare dischargeable.

OzN CHzCHzOH CHzCHzOH EXAMPLE 8 CHroHioH a Diazotization is effected asin Example 6.

Coupling.N,N-di-(beta-hydroxyethyl)cresidine (4.50 g.) is dissolved in150 ml. of water and 2.0 ml. of 37% hydrochloric acid contained inone-liter beaker, and the solution is cooled to below 0 C. by additionof ice. The diazonium solution is now added gradually over a period of10 minutes, the reaction mixture being stirred vigorously and kept at atemperature below 0 C. by addition of ice as necessary. A green-blueprecipitate forms, and the slurry is stirred for two hours at 0-14 C.There is then added, with good stirring, a solution of 60.5 g. of sodiumacetate in 200 ml. of water, which neutralizes the mineral acid. Thereaction mixture is then stirred for twenty hours at room temperature,after which the dye is isolated by filtering, washing neutral to litmus,and drying in an oven at 50 C. The product weighs 5.00 grams, indicatinga yield of 52.8% of theoretical.

Dispersion is efiected as in Example 3.

Dyeing.-The product dyes acetate, nylon and Dacron in gray-blue shades.

EXAMPLE 9 OHzCHgOHzCHa CHgOHzOH Diazoti zation is eifected as describedin Example 6.

C0upling.-Nbutyl-N-phenyl ethanolamine (3.86 g.) is dissolved in 150 ml.of water and 2.0 ml. of 37% hydrochloric acid contained in a one-literbeaker. The mixture is cooled to 0 C. by addition of ice, and thediazonium solution is then added gradually, with good stirring, over aperiod of 20 minutes, adding ice as necessary to keep the temperaturebelow 2 C. A blue-green precipitate is formed, and the mixture isstirred for one hour with the temperature between 0 C. and 14 C. Themineral acid is then neutralized by gradually adding a solutionconsisting of 60.5 g. of sodium acetate in 2000 ml. of Water. Themixture now tests gray to Congo red. Stirring is continued for 18 hoursat room temperature, after which the dyestufi is collected byfiltration, washed neutral to litmus, and dried at 50 C. The yield is4.56 g., equivalent to 51.4% of theory.

Dispersion of this dye is efiected as described in Example 3.

Dyeing.--This dye produces a blue shade on acetate and Dacron and agray-green shade on nylon.

EXAMPLE 10 Diazotization.-2-amino-4,6-dinitrobenzothiazole (4.80 g.) ispulverized and dissolved in 50 ml. of phosphoric acid contained in a 250ml. three-neck flask equipped with thermometer and mechanical stirrer.The mixture is cooled in an ice-salt bath, and nitrosyl sulfuric acid,prepared by dissolving 1.40 g. of sodium nitrite in 15.0 ml. of 96%sulfuric acid, is added over a period of 10 minutes during which timethe temperature of the reaction mixture is kept between l4 C. and 9 C.Stirring is continued at 10 C. for 4 hours, and then 30 ml. of water isadded dropwise, keeping the mixture at below -10 C., and the mixture isthen stirred for an additional 1 /2 hours at 10 C.

Coupling.Diethy1 aniline (2.98 g.) is dissolved in ml. of water and 2.0ml. of 37% hydrochloric acid contained in a 1.5 liter beaker. Thediazonium solution, prepared as above described, is added over a periodof five minutes, adding ice as necessary to keep the reaction mixture at0 C. A green precipitate forms, and the resulting slurry is stirred for18 hours. The mineral acid is neutralized by gradual addition of asolution of 105.2 grams of sodium acetate in 500 ml. of water; afterthis treatment, the mixture tests gray to Congo red. After stirring foranother hour or so, the solid dyestufi is collected by filtering,washing with water until neutral to litmus, and drying at 50 C. A yieldof 4.70 grams, equivalent to 58.8% of theoretical, is obtained.

Dispersion is efiected as described in Example 3.

Dyeing-The product of this example colored acetate and Dacron in blueshades and nylon in a green shade.

EXAMPLE 11 Diazotization is effected as described in Example 3.

C0upZing.Phenol (1.88 g.) is dissolved in 50 ml. of 0.5 N methanolicsodium hydroxide, and this solution is added dropwise, over a 25 minuteperiod, to the vigorously stirred diazonium solution which is maintainedat a temperature between 16 C. and 8" C. by means of an ice-saltmixture. An orange precipitate forms. The reaction mixture is stirredfor one hour at sub-zero temperatures maintained by an ice-salt bath,and then for another hour at ice-bath temperature. It is then pouredinto 500 ml. of ice and water and stirred for a short time. Theprecipitate is filtered, washed neutral to litmus, and dried in a vacuumdesiccator. The yield is 4.84 g. of orange solid, equivalent to 70.0% oftheoretical.

Dispersion is effected as described in Example 3.

Dyeing.The product of this example dyes acetate and Dacron in goldshades.

Diazotization is efiected as described in Example 6.

Cupling.N-ethyl-N-(2,3 dihydroxypropyD-rn-toluidine (4.18 g.) isdissolved in 2 ml. of 37% hydrochloric acid and 150 m1. of water. Thesolution is cooled to 0 C. by adding ice, and the diazonium solution isthen added with stirring over a period of 1 0 minutes, adding ice asnecessary to keep the mixture at about 0 C. A blue precipitate forms,andthe mixture is stirred for /2 hour, keeping the temperature between 0and 15 G. Then a solution of 6 0.5 g. of sodium acetate in 200 ml. ofwater is added to neutralize the mineral acids.

The reaction mixture (testing gray to Congo red) is stirred over nightat room temperature and filtered. The blue solid is washed with wateruntil neutral to litmus, and thendried at 60 C. The yield is 4.95 g.,corresponding to 53.8% of theoretical.

Dispersion is effected as in Example 3.

Dyeing.The product dyes acetate, nylon and Dacron in blue shades. Thedyeings are dischargeable. "I'he dyeings on acetate exhibit goodfastness to gas, light, sublimation, and washing.

CHgCHz CHzOHOHOHzOH.

EXAMPLE 13 V s 011,011,011 U N=N N mlrqkcm CHzCHflOH N0: [I

Diazotization is efiected as described in Example 3.

C0upling.- 2-(N,=N di beta-hydroxyethyl) amino-4- acetylaminoanisole(5.36 g.) is dissolved in a mixture of 2.0 ml. of 37% hydrochloric acidand 64 ml. of water. The solution is cooled to about 0 C. by addition ofice, and the diazonium solution is added slowly over a period of 10minutes, maintaining the reaction mixture at 0."v C. by suitableadditions of ice. A slate-blue precipitate forms. After stirring for onehour at about 0 C., the mixture is neutralized to Congo red by additionof sodium acetate solution. After another two hours of stirring, theproduct is isolated by filtering, washing neutral to litmus, and dryingat 50 .C. The yield is 4.9,gi, corresponding to 47.2% 0f theoretical.

Dispersion isefiected as in Example 3.

Dyeing.The product dyes acetate a grayish-green and yields gray shadeson Dacron and nylon.

Diazotization is eifected as described in Example 6.

Couplingr N-ethyl-N-beta-cyanoethyl aniline (3.48 g.) is dissolved in 2ml. of 37 hydrochloric acid and 150 ml. of water. 7 The solution iscooled to about 0 C. by addition of ice, and the diazonium solution isadded withgood stirring over a period of 11 0 minutes, keeping thetemperature of the mixture at about 0 C., by addition of ice as needed;a very dark violet precipitate forms. The mixture is stirred for twohours, neutralized with sodium acetate, and stirred over night. Byfiltering, washing neutral, and drying at C., there is obtained 5.02grams of product, corresponding to a yield of 59.2% of theoretical. I I

- Dispersion is effected as described in Example 3.

Dyeing.--The product dyes acetate a violet shade, Dacron areddish-violet shade, and nylon a gray-w'olet shade. The dyeings onacetate are dischargeable and show good fastness to light, gas, andsublimation.

The term Dacron, as used in this specification, designates the ethyleneglycol terephthalate linear super-polyester fiber manufactured-and soldunder that name by E. I. du Pont de Nemours and Co., Inc. The termnylon, as used in this specification, designates the linearsuperpolyamide fibers derived from epsilon-caprolactam or fromhexamethylene diamine adipate. The term acetate as used herein todesignate textile fibers refers to fibers spun from acetylatedcellulose. Marasperse N is a sodium lignin sulfonate distributed by theGeneral Dyestuffs Corporation and is understood to be an N-acylation'product derived from higher fatty acid chlorides '(palmitic and oleic)and -N-methyl taurine. It is sold as the sodium salt, and thus has thestructure References Cited in the file of this patent UNITED STATESPATENTS 2,868,775 Straley et al Jan. 13, 1959 FOREIGN PATENTS 707,599Great Britain Apr. 21, 1954 OTHER REFERENCES Dyson et al.: Chem.Abstracts, volume 21, page 2688 (1927).

Hunter et al.:

Chem. Abstracts, volume 25, page .104 ("193 1) i

1. 2-AMINO-4,6-DINITRO-BENZOTHIAZOLE.